Cardiovascular diseases are the leading causes of morbidity and mortality in the United States. On the basis of an interplay of genetic and environmental factors, these diseases appear to be rooted in childhood. Recent reports implicate the intrauterine nutritional environment regulating fetal growth as a determinant of adult cardiovascular disease. According to this concept, impaired fetal growth, with consequent lower birth weight, results in alteration in organ structure and subsequent functional impairment in later life. Higher blood pressure (BP) has been suggested as the possible link between compromised intrauterine growth and the long-term risk for cardiovascular disease. Despite the many reports which appear to support the low birth weight - high BP hypothesis, this concept is in conflict with the body of data on the association of BP with body size in childhood, adolescence, and adulthood which consistently demonstrates a direct relationship between body weight and BP. To examine the low birth weight - high BP concept, the investigators propose a prospective study on a cohort of children who were well characterized at birth. In 1988, data on weight, length, BP, gestation and maternal health were obtained on 1124 newborn cases representing a range of birth weight and gestational age. They propose to re-examine these children at age 11-13 years to test the overall hypothesis that birth weight, as well as other newborn measures of intrauterine growth, does not correlate with BP at age 11-13 years. The aims of this project are to: 1) determine if birth weight contributes to BP and/or body size in childhood; 2) determine if the duration of intrauterine growth in terms of gestational age contributes to BP and body size; 3) determine if newborn ponderal index, a measure of relative fetal growth, contributes to BP and body size; and 4) determine the relative contribution of newborn measures of birth weight, gestational age, BP, ponderal index, and maternal health to BP and body size in late childhood. The results of this prospective study will contribute an objective body of data to this important issue. If birth measures reflecting intrauterine exposure do contribute significantly to BP in later childhood, then studies focused on the mechanisms regulating this risk will be justified. Alternatively, if post-natal/childhood parameters are the major determinants of later BP, then efforts should focus on effective preventive strategies in childhood, such as obesity.